Banded Agate (specifically Sardonyx or Carnelian Agate)

Physical Properties

Hardness: 6.5-7 on Mohs scale; Color: Concentric bands of orange, white, and translucent; Luster: Vitreous to waxy; Crystal Structure: Trigonal/Microcrystalline; Cleavage: None; Specific Gravity: 2.58–2.64.

Formation & Geological History

Formed in cavities (vesicles) of volcanic rocks through the deposition of silica-rich groundwater. Over time, layers of microcrystalline quartz create the distinctive banding. These can range from millions to over a billion years old.

Uses & Applications

Commonly used in jewelry (cabochons, beads), decorative carvings, paperweights, it's also a popular collector's item and used in metaphysical practices.

Geological Facts

Ancient Romans used banded agate signet rings because wax would not stick to it. Agate is named after the Achates River in Sicily where it was first discovered.

Field Identification & Locations

Identified by its distinctive parallel or concentric bands and toughness. Commonly found in Brazil, India, and the Lake Superior region of North America. Look for the 'waxy' texture and light transparency on thinner edges.

Identified on: 4/13/2026

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